It’s hard to say that Brady Skjei is taking this in stride, because he’s never been anywhere close to steps these big.

But the Rangers rookie defenseman is unquestionably a cool and calm character, both on and off the ice, and being part of the group that is filling in for injured captain Ryan McDonagh is just something he’s doing as well as he can.

“Mentally, I feel like I can play [in the NHL] since the first call-up; I thought I played pretty well and right then I knew I could play here,” Skjei said after Friday’s practice, his team preparing for the regular-season finale against the Red Wings at the Garden on Saturday afternoon. “So I’m just taking it day-by-day.”

That’s less a cliche than it is just the way Skjei has been forced to approach this season. He’s on his fifth different call-up of the season with Saturday representing his seventh career NHL game. The 22-year-old from Minnesota was the team’s first-round pick (28th overall) in 2012, and his 6-foot-3, 215-pound frame only supplements his wonderful skating ability.

“I think every time he’s on the ice, he grows as a player, he gets more experience,” said coach Alain Vigneault. “I think we can all see it in his skill set, the skating ability, the beating-the-first-forechecker ability. It’s like any other young player in the league, you have to know when to go, when to give, when it’s the better time to stay back and make the right reads.”

Yet after the Islanders swept the four-game season series against the Blueshirts with Thursday’s 4-1 victory, the Brooklynites over their final two games control how the first-round matchups will play out. In order for the Rangers to leapfrog back into third place — and into a series with the red-hot Penguins — they would need to beat the Red Wings, and the Islanders would need to get two points or fewer against the Sabres and Flyers on Saturday and Sunday at Barclays Center.

“We’re aware of every possibility, but they’re both really good teams,” center Derick Brassard said of the Penguins and Panthers. “You can’t control who you’re going to play. We’re going to try to win the game, and whatever the Islanders are going to do in the next two games is going to decide what happens.”

And possibly whatever comes of Skjei’s game can determine how that first-round series goes. With McDonagh out, the only natural left-side defensemen the team has are Keith Yandle and Marc Staal. Right-hander Dan Girardi will miss Saturday’s game with his upper-body injury, but is expected back for the start of the playoffs, joining Kevin Klein, Dan Boyle and Dylan McIlrath on that side.

Yet McDonagh has been the team’s best blueliner all season, and it’s on the rookie Skjei to try to ease his loss — for however long it lasts.

“Personally, it’s good for me,” Skjei said. “But you lose a guy like McDonagh [or] Girardi, it definitely hurts the team a little bit. So I’m just trying to do my best and see what happens.”